Remove Duplicates from Sorted Array — C++

// Time:  O(n)
// Space: O(1)

class Solution {
public:
    int removeDuplicates(vector<int>& nums) {
        int last = -1;
        for (const auto& num : nums) {
            if (last == -1 || nums[last] != num) {
                nums[++last] = num;
            }
        }
        return last + 1;
    }
};